1. Field of the Invention
The present invention relates to a method for manufacturing a semiconductor device using a silicon-on-insulator (SOI) substrate.
2. Description of the Related Art
Demands for higher integration, higher operation speed, higher performance, and lower power consumption of a semiconductor integrated circuit have been more stringent, and in response to such demands, a transistor using an SOI substrate has attracted attention as an effective means that can take the place of a bulk transistor. Higher operation speed and lower power consumption of a semiconductor device can be expected more in the transistor using the SOI substrate than in the bulk transistor because a semiconductor film is formed over an insulating film in the transistor using the SOI substrate, and accordingly parasitic capacitance can be reduced and generation of leakage current flowing through the substrate can be suppressed. In addition, since the semiconductor film used as an active layer can be formed thin, a short channel effect can be suppressed; thus, an element can be miniaturized and higher integration of a semiconductor integrated circuit can be realized accordingly.
As one method for manufacturing an SOI substrate, a method is given in which a semiconductor film is attached to a substrate with an insulating film interposed therebetween, such as UNIBOND (registered trademark) typified by Smart Cut (registered trademark), ELTRAN (epitaxial layer transfer), a dielectric separation method, or a PACE (plasma assisted chemical etching) method. The above-described attaching methods make it possible to form a high-performance integrated circuit using a single crystal semiconductor film over an inexpensive glass substrate.
For example, Patent Document 1 (Japanese Published Patent Application No. 2004-087606) has disclosed a method for manufacturing an SOI substrate by attaching a semiconductor film separated from a bulk semiconductor substrate to a glass substrate.
In Patent Document 2, a method for improving crystallinity of a semiconductor thin film layer transferred to a glass substrate by laser light irradiation is disclosed.